Motor control system



April 30, 1935. 0. K. MART! 1,999,772

MOTOR CONTROL SYSTEM Filed Sept. 10, 1952 Patented Apr. 30,1935 A1,999,772

MOTOR CONTROL SYSTEM Othmar-K. Marti, Wauwatosa, Wis., assignor toAllis-Chalmers Manufacturing Company, Milwaukee, Wis., a corporation ofDelaware Application September 10. 1932, Serial No. 632,563

- 14 Claims. (01. 172-274) This invention relates to improvements in themotors in which the motor armature currents are control of electricmotors and more particularly controlled by means of an electrondischarge de- .to the control of polyphase alternating current vice orof a plurality'of such devices.

motors in which the current in the armature Objects and advantages otherthan those above windings is not conducted through the usual set forthwill be apparent from the following de- 5 type of commutator. scriptionwhen read in connection with the ac- Polyphase alternating currentmotors without companying drawing, the single figure of whichcommutators are known in the art, such motors diagrammaticallyillustrates one embodiment of generally comprising a rotating fieldexcited with -the present invention, in which the motor is so directcurrent and a fixed armature provided connected as to present seriescharacteristics. 10

with suitable windings having their terminals Referring moreparticularly tothe drawing by directly connected with a polyphasealternating characters of reference, reference numeral 6 supply line orwith the secondary windings of a designates a polyphase alternatingcurrent supply transformer. Such motors generally operate at linerepresented as a three-phase line, this type only one speed or, by useof different special of line being;most frequently met in commercial 15means, operate at a limited number of operating practice Supply line 6supplies current toa speeds .related to the frequencyof the supply motorhaving a field winding I and a. plurality voltage wherefore such motorsare known as syn-1 of armature windings 8, 9 and II, 9.11 windingschronous motors. By controlling the armature being ofthe constructionusual in the art of socurrents of a motor of the above character calledsynchronous motors. It is assumed that 20 through an electron dischargedevice, it is poswinding 1 is rotating and is therefore energized sibleto operate such motor at a large number of through slip rings l2, 13.The field of the mooperating speeds or even at continuously varitorenergized by winding 1 maybe of the smooth able speeds. The motor maythen' be so conscore or of the salient pole type and may present 5nec'ted as to operate with series, shunt'or comany desired number ofpairs of poles upon which pound characteristics. Such results werehereportions of winding 1 are distributed as is welltofore only obtainedby the use of commutator known in the art. windings 8, 9 and Hareasmotors which present the well known disadvansumed to be assembled inthe stator of the motor tages of high cost, commutation difficulties andand are each divided into a plurality of portions voltage limitations.The use of an electron dissuch as 8a. 8!), etc., connectedto'form-aneutral 30 charge device presents another advantage in that point- Each0 the ev l portions o d s it also permits starting and reversing of themo- 8, 9 and I I may be arranged as turns enclosedyin tor without theuse of switching devices and withone slot or may be distributed amongthe slots out loss of energy. of the armature to insure uniformity inthe torque 3,3 It is, accordingly, among the objects of the of themotor'as is well knownin the art. Windpresent invention to provide acontrol system gS rece g Current SimultaneOllSlY for a P for alternatingcurrent polyphase motors withticular .degree of rotation of the motormay be out commutators to permit operation thereof at inserted in thesame slots or may be inserted into ari ble operatingspeeds. separateslots of the armature. Each portion 40 Another object of the inventionis to provide may also be divided into a plurality of windings 40' acontrol system for variable speed polyphase constituting poles in equalnumber to the poles alternating current motors to permit operation offield winding 1.. thereof at high voltages, V) Each of armature windingportions such as 8a, Another object is to provide a control'system' 9aand Ha are severally connected with anodes for variable speed polyphasealternating current Such as IE0, 26a and 36a of an electron dis- 45motors whereby such motors are brought up to charge-device I! of thearcing type operable as operating speed without the use of switchingdean electric current rectifier and provided with vices, a cathode 22.The neutral points of windings Another object is to provide a controlsystem 8, 9 and H are connected with the secondary for variable speedpolyphase alternating current windings 14a, Mb, I 40 of a transformerhaving 50 motors permitting reversal of the direction of the a primarywinding l5 connected with line 6. rotation thereof without the use ofswitching de- Winding I4- is shown as being connected in star vices. vbut such winding may be connected in zigzag or Another object is toprovide a control system in other well known connection. The neutral forvariable speed polyphase alternating current point of winding I4 isconnected with slip ring I! thereto. Rectifier ll is provided withgroups of control electrodes I8, 28 and 38 which are en- "ergized at'anegative potentialrelative to the potential of cathode 22 from a batteryis through current limiting resistances 20 and 2 The control electrodesmay also be energized at a positive or negative potential from apotentiometer 21 connected across battery I! and a second7battery 38,

motor from line 8. s The potential impressed on may also be obtained byadjustment of shifter 29. Il. Such adjustmentot the armature currentgives a corresponding adjustment in the range of torques and of speedsat which the andsimultaneously receive alternating potentials, motoroperates, Another means for controlling from secondary winding 3| or atransformer havthe characteristics of the motor resides in shirting aprimary winding 29 connected with line 6. the position of distributors23, 2d and II with Such energization is controlled by means ofdisrespect to the position of the armature windtributors 23, 24,25having their brushes mounted ingsby means or lever U. .The particulararmaon the shaft of the motor and their segments ture winding portionsreceiving current may thus spatially adjustable by means of a lever ll.g

In operation, assuming the system to be'con nected as shown andmomentarily in the posi-" ,tion indicated on the drawing, line 6energizes winding l5 which induces alternating poten tials in theseveral portions of winding ll. All the control "electrodes of rectifierH, with the be selected with respect to the position oi the ofleldwinding, thereby varying the torque caused 1,

by the interaction 0! the currents in such windings.

Whenthe motor is at rest, flow ot ourrentthere-' through is prevented byopening switches", 34, and 38 to permit energization only of the controlexceptio'n ot control electrodes Illa, 2a and 38a, electrodes ofrectifier llfat the negative potential receive a negative potentialfrombattery l9 and, therefore, prevent the flow of current through theanodes associated therewith. Control electrodes l8a, 28a and 38areceivea direct current potential from potentiometer; 21 and receivethree-phase alternating current potentials from winding 3|. Transformer29, 3|, which may be constructed as a phase shifter, is so adjusted thatcontrol electrodes lla, 28a and 38a sequentially A through slip ring l1,windingv I and slip become positive with respect to cathode Z2 when 7associated anodes l 6a, 26a and 36a respectively.

are 'energized at positive potentials from windof battery l9. Duringstarting of the motor, the

current therethrough may be maintained within any desired range orvaluesby adjustment of potentiometer 2T0! otphase' shifter 29, 3l-. The

current may be reduced Iurthergby closing onlyswitches 33, 34, 38thereby permitlugs a, "14b and llciresp ectively connected "windingsotthe motor produces the maximum .th'erewith. Anodes lGd, 26a and 355:thus sequentially carry current during each cycle ot the supply linevoltage, such currents flowing through windings 8a, 9a and Ila andcombining to form direct current flowingfrom cathode 22:

ring I! to the neutral point ,of winding I. The -iiow or, currentthrough windings-I, 8a, 9a and Ho during one-or more cycles of thesupply line voltage produces atorque which causes rotation of field 1,Such rotation also causes the brushes'of the. distributors to leavesegments 23a, flaand 25a and 25b thereoL'eCo'ntr'ol electrodes Isa, noand 18a thus are negatively energized from battery l3 of the directionoirotation of the motor without the use of switching devices and withoutloss of energy. It will be understood-that switches may be provided fordisconnecting the motor from and to come into contact with segments 23b,Illa the supply line but such switches will be used for openingthecircuit without interruption 0! carrent except upon occurrence ofshort circuits or other'disturbanoein the system. I *Although but oneembodiment of the ingssubsequent cycles-oi the supply line voltage.'inventi'onhas been illustrated and described, it Control electrodes'l8b, 28b'and 38bthen receive direct current potential frompotentiometer" 21 and alsoreceive alternating current potentials fromwinding 3| thereby permitting operation of the associated anodes lib,25b and 3b in amenner similar to that previously'described for anodeslta, "sand 35a. Currents thus flow through windings 1, lb sban'd .l lb,thereby producing atorque on the motor and causing further rotaply linev01tage..-A ny qf'the means knownin thear't for the control ofrectifiersmay be used c to regulate theaniounti'ot current supplied to the presentwill be apparent to those skilled in the moat variouschanges andmodifications may be made &Patent 1. In s control system Iona motorhaving a plurality of stator windings and a rotoriwinding, a polyphasesupply line, a transformer connected with saidli'ne, the several phasesof the secondary winding of said transformer forming a neutral point andbeing severally connected with the stator windings, an electrondischargedevice having anodes anda cathode, the anodes beingconnect'edwith the stator windings and the cathode being connected withone terminal of the rotor winding, the other terminal ot'the rotorwinding being connected with the neutral point of said I plurality ofstator. windings and a rotor winding,

a polyphase supply line, means connecting the stator windings with saidline, an electron discharge device having anodes with associated controlelectrodes and a cathode, the anodes being connected with the statorwindings and the oathode being connected with the rotor winding, atransformer connected with said line, a source of direct currentconnected with the cathode and with said transformer, and a plurality ofdistributors connecting the control electrodes with said transformer tocontrol the operation of said de- VIC-e.

3. In a control system for a motor havinga plurality of stator windingsand a rotor winding, 9.- polyphase supply line, means connecting thestator windings with said line, an electron discharge device havinganodes with associated control electrodes and a cathode, the anodesbeing 6. .In a control system for an electric motor havconnected withthe stator windings and the cathode being connected with the rotorwinding, a

transformer connected with said line, a source of direct currentconnected with the. cathode and with said transformer, a plurality ofdistributors connecting the control electrodes with said trans: formerto control the operation of said device, and means for varying theposition of said distributors relative to the positions of the statorwindings.

4, In" a control system for a motor having a plurality of statorwindings and a'rotor winding, a polyphase supply line, means connectingthe stator windings with's'aid line, an electron discharge device havinganodes with associated control electrodes and a cathode, the anodesbeing connected with the stator windings and the cathode'being connectedwith the rotor winding, a source of direct current, means connectingsaid source with the cathode to obtain a variable potential from saidsource relative to the potential of the cathode, a transformer connectedwith said line and wi'h the second said means, and a plurality ofdistributors sequentially connecting the control electrodes and saidtransformer to'control the" operation. of said device.

5. In a control systemfor a motor having a plurality of stator windingsand a rotor winding,

'a polyphase sup ly line, means connecting ,the

connected with the stator windings and the oathode .being connected withthe rotor winding, a

source of direct current, means connecting-said source with the cathodeto obtain avariable potential from said source relative tothe potentialof the cathode, a phase shifting transformer connected with saidline andwith the second said means, a plurality of distributors connected with'the control electrodes, switches severally connecting the secondarywindings of said transformer with said distributorssaid distributorsbeing operated by the motor for sequentially impressing a potentialpositive to that of the cathode on the control electrodes, and means forshifting the positions of said'diistributors relative to the position ofthe stator windings.

ing a field excitation winding and a plurality of armature windings eachcomprising a plurality of angularly displaced sections connected to forma neutral point, a source of polyphase alternating current connectedwith said field winding andhaving the phases thereof severally connectedwith said neutral points, electron discharge means having a cathodeconnected with said field winding and a plurality of anodes severallyconnected with said windingsections, a pluralityof control electrodesseverally associated with said anodes, and means having connections withsaid control electrodes operable to impress potential thereon of suchsign and magnitude and during such recurring periods as to control theinitiation of flow of current fromsaid source of current sequentiallythrough the respective sections of said armature windings by way of saidanodes and cathode.

7.-In a control system for an electric motor having a field excitationwinding and a plurality of armature windings each comprising a pluralityof angularly displaced sections connectedto ,form a neutral point, asource of polyphase altarnatingcurrent connected with said fleldwindingand having the phases-thereof severally connected withsaid neutralpoints, electron discharge means comprising a cathode connected withsaid field winding, a plurality of anodes severally connected withthss'ections of'said armature windings, and a plurality of controlelectrodes severally associated with said anodes, a source of currenthaving connections with said cathode and Y with said control electrodesfor continuously impressing on the latter potential of such sign andmagnitude as to prevent flow of current through 'the sections of saidarmature windings by way of said anodes, and means having connectionwith said source of alternating current and with said control el:ctrodesoperable to impress potential on the latter of such sign and magnitudeand at" such recurring periods as to permit flow of current from saidsource of alternating current sequentially through the respectivesections of said 'a neutral point,,a source of polyphase alternatingcurrent connected with .said field winding and" having the phasesthereof severally connected with said neutral points, electron dis-'charge means having a cathode connected with said field winding and aplurality of anodes severally connectedwith said winding s:ctions, a

plurality of control electrodes severally associated with said anodes,and means having connections with said control electrodes operable toperiodically apply potential thereto of such sign and magnitude and'duringsuch recurring'periods.

as to control the moments of initiation of flow of current from saidsource sequentially through the respective sections of said armaturewindings by way of said anodes and cathode, the said means includingdistributor switch means for varying the moments of application of saidpotential to said control electrodes.

9. In a control system for an electric v motor "having a fieldexcitationwinding anda plurality of armature windings each comprisingaplurality.

of angularly displaced sections connected to form a neutral point, asource of polyphase alternating ed with said field winding and aplurality of '75 i 45 the moments of application of said anodesseverally connected with said winding sections, a plurality of controlelectrodes severallyarmat re windings by way of said anodes and,cathode, and distributor switch means included in the connections ofsaid transformer with said control electrodes for varying the moments ofapplication of said potential to the said control electrddes. 9

10. In a control system for an electric motor having a field excitationwinding and a pluralityof armature windings each comprising a pluralityof angularly displaced sections connected to form a neutral point, asource of polypha'se v alternatingtcurrent, a transformer havingconnections with said source of current and, comprising a polypha sewinding connected to form a neutral point connection with said fieldwinding and having the phase sections thereof severally con ncted withthe neutral point of the respective said armature windings, electrondischarge means comprising a cathode'connected with said field windingfaplurality of anodes severally connected with the sections of saidarmature windings, and a plurality of control electrodes severallyassociated with said anodes, means comprising a transformer havingconnectionswith said source of current and with said control electrodesoperable to periodically; apply potential thereto of such sign andmagnitude and during such recurring periods as to control themoments ofinitiation of flow of, current sequentially through 40 the respectivesections of said armature windings by way of said anodes. and cathode,and distributor switch means included in the connectionsof the last saidtransformer with said control electrodes and operated by said motor forvarying potential to the said control electrodes,

11. In combination with a polyphase alternating current circuit, and anelectric motor comprising a plurality of armature windings severally 50connected with the phases of saidcircuit to be supplied with operating,current therefrom, of an electron discharge device comprising apluralityof anodes severally included in the pera ive connections of saidwindings with thir hases of said 55 circuit and control electrodesseverally associated with said anodes, a transformer connected with saidcircuit, a source of direct current connected .with said transformer,and means comprising element,operated by said motor for sequentially toconiiecting the said controLelectrodes with said transformer at suchrecurring moments as to thereby control the moments of initiation offlow of said operating current sequentially through said windings. H g

- $2. The combination with a polyphase altern ing current circuit, and.an electric motor comprising a plurality of armature windings-severallyconneeted with the phases of said circuit'to be by control the momentsof initiation of said flow supplied with operating current therefrom, of

an,electron discharge device comprising aplurality of anodes severallyincluded in the opera- 'tive connections of said windings withthe phasesof said circuit and control electrodes severally 'associated with saidanodes, atransformer connected with said circuit, a source of directcurrent connected with said transiormer, means comprising an elementoperated by said motor for sequentially connecting the said controlelectrodes wlth'said transformer at such recurring moments as to erebycontrol the moments of initiation of flow of said operating currentsequentiallythrough said windings, and'means tor adjustingtheflrst saidmeans in such sense as to vary the moments of said connections of saidcon-- trol electrodes with said transformer, to thereby control thespeed of rotation of said motor. 13. The combination with a polyphasealternating current circuit, and an electric motor comprising aplurality of armature windings several- 1y connected with .the phases ofsaid circuit to be suppliedwith operating current therefrom, of anelectron discharge device comprising a plurality of anodes severallyincluded in the operative connections of said windings with e phases ofsaid circuit and control electrodes severally associated with saidanodes, means for exciting said control electrodes comprising atransformer energized from said circuit to control the flow of 30 saidoperating current, means comprising an element operated by said motorfor sequentially coni necting the first said means with said controlelectrodes at such recurring moments as to there- 35 of currentsequentially through said windings. and means for adjusting the secondsaid means in Q such sense as to vary the moments of said connectionsoithe first said means with said control electrodes relativeto the voltagefrequency of said circuit, to thereby regulate the speed of rotation ofsaid motor.

14. lrhe combination with a polyphase alter- K nating, current circuit,aml'an electric motor comprising a plurality ot armature windingsseverally connectedwiththe phases of said circuit to besupplied withoperating current therefrom, of an electron discharge device comprising7 aplurality of anodes severallysincl uded insaid operativeconnectionsof said windings with said 0 uit and control electrodesseverally associated m said anodes, means for exciting said controlelectrodes pomp a transformer energized from said circuit to control theflow of said oper-- ating current, distributor switch means operated bysaid motor for sequentially connecting the first said means withsaidcontrolelectrodes at'such recurring moments-as to thereby controlthemements of initiation of said'flow of current sequentially 09811 saidwindings, and means for adjusting the second said means in such sense aslac-vary the moments otsaidconnections of the first said means with saidcontrol electrodes rela-. tive to the voltage frequency of said circuit,to thereby-regulate the speed of rotation of said motor. v V l K. HARTI.

